How is the term "oxygen toxicity" defined?

The term "oxygen toxicity" is defined as a condition caused by breathing elevated partial pressures of oxygen. When divers breathe oxygen at higher pressures, such as when using enriched air (Nitrox) at greater depths, the increased partial pressure can lead to toxic effects on the central nervous system and the lungs. Symptoms may include visual disturbances, respiratory issues, and even seizures in severe cases.

The other options do not accurately reflect the definition of oxygen toxicity. Physical exertion underwater, while it can affect a diver's status, does not cause oxygen toxicity. An allergic reaction to diving equipment is unrelated to the effects of oxygen pressure. Lastly, low oxygen levels would not cause oxygen toxicity; instead, they can lead to hypoxia, a different condition entirely. Thus, the correct definition distinctly ties oxygen toxicity to the effects of increased oxygen pressure.